story = "Once upon a time, in a land far away, lived a brave knight named Arthur."
# 计算单词数
print(len(story.split()))
# 查找主角位置
print(story.find('Arthur'))
# 替换主角名
print(story.replace('Arthur', 'ZR'))
# 全部大写
print(story.upper())
# 全部小写
print(story.lower())
